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arXiv 2023年

作者： Xu, Fan Su, Jinghong Lan, Bin Zhao, Peng He, Yurong Sun, Chao Wang, Junwu School of Energy Science and Engineering Harbin Institute of Technology Harbin150001 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences P. O. Box 353 Beijing100190 China School of Chemical Engineering University of Chinese Academy of Sciences Beijing100049 China Innovation Academy for Green Manufacture Chinese Academy of Sciences Beijing100190 China Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering Ministry of Education Department of Energy and Power Engineering Tsinghua University Beijing100084 China Department of Engineering Mechanics School of Aerospace Engineering Tsinghua University Beijing100084 China

Direct numerical simulations are performed to explore the effects of the rotating direction of the vertically asymmetric rough wall on the transport properties of Taylor-Couette (TC) flow, up to a Taylor number of Ta = 2.39×107. It is shown that, compared to the smooth wall, the rough wall with vertical asymmetric strips can enhance the dimensionless torque Nuω. More importantly, at high Ta, clockwise rotation of the inner rough wall (where the fluid is sheared by the steeper slope side of the strips) results in a significantly greater torque enhancement compared to counter-clockwise rotation (where the fluid is sheared by the smaller slope side of the strips), due to the larger convective contribution to the angular velocity flux. However, the rotating direction has a negligible effect on the torque at low Ta. The larger torque enhancement caused by the clockwise rotation of the vertically asymmetric rough wall at high Ta is then explained by the stronger coupling between the rough wall and the bulk, attributed to the larger biased azimuthal velocity toward the rough wall at the mid-gap of the TC system, the increased turbulence intensity manifested by larger Reynolds stress and a thinner boundary layer, and the more significant contribution of the pressure force on the surface of the rough wall to the torque. Copyright © 2023, The Authors. All rights reserved.

关键词： Direct numerical simulation

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Sustainable hydrogen production from coal tar residue via supercritical water gasification

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Journal of Cleaner Production 2025年 519卷

作者： Jingui Bai Yu Wang Shi Liu Libo Lu Wen Cao Ting Chen Yunan Chen Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an 710049 China Ningxia Baoting New Materials Technology Co. Ltd. Yinchuan 751400 Ningxia China

Hazardous wastes such as coal tar residue (CTR) pose a serious hazard to the environment and human health. In the context of ‘carbon peak and carbon neutrality’, the conversion of wasted resources into energy to replace fossil fuels is in line with the requirements of future social development. Supercritical water (SCW) offers a promising approach for converting hazardous waste CTR into energy. This article combines supercritical water gasification (SCWG) technology with the efficient utilization of CTR for the first time, providing a scientific solution for reducing environmental pollution and preparing hydrogen. In this article, we systematically investigated the effects of temperature (540–700 °C), residence time (5–60 min), material concentration (3 wt%-11 wt%), and six different catalysts on CTR SCWG. Experimental results indicate that higher temperature, longer reaction time, and lower CTR concentration are beneficial for gasification. When the temperature, retention time, material concentration, and catalyst are set at 700 °C, 60 min, 3 wt%, and K 2 CO 3 respectively, most of the carbon in the CTR is converted into small molecular gases. The carbon gasification efficiency (CE) reaches 94.44 %, while the H 2 yield attains a value of 67.56 mol kg −1 . Finally, based on the analysis results of gas, liquid and solid products, the SCWG mechanism of CTR is summarized.

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Efficient Water Reforming of Biomass to H2via Well-Organized Redox-Neutral Cleavage of C−C, O−H and C−H Bonds

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Angewandte Chemie 2024年第4期137卷

作者： Wen-Min Zhang Prof. Yang Li State Key Laboratory of Multi-phase Flow in Power Engineering and Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an 712046 China

Hydrogen (H 2 ) is a clean and environmentally friendly energy carrier. The depletion of fossil fuels makes renewable H 2 production highly desirable. Water reforming of renewable biomass to hydrogen, with a relay of natural photosynthesis to biomass, would be an indirect pathway to realize the ideal but extremely challenging photocatalytic overall water splitting to hydrogen, with favorable thermodynamics. Since the seminal work of water reforming of biomass in 1980, great endeavors have been made. Nevertheless, hitherto, the entire kinetic pathway has been elusive, which seriously limits the reforming processes. Using a designed well-organized redox-neutral cleavage of C−C, O−H and C−H bonds enabled by photoelectrocatalysis, here, we show the efficient water reforming of biomass to hydrogen at room temperature, with a yield up to 93 %. The clear insights into the kinetic pathway with oxidation of carbon radicals to carbon cations as the indicated rate-determining step, would cast brightness for efficient and sustainable hydrogen production to accelerate the hydrogen economy.

关键词： hydrogen production biomass reforming photoelectrocatalysis iron catalysis redox-neutral chemical bonds cleavage

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Degradation of polyethylene terephthalate (PET) and polypropylene (PP) plastics in seawater

DeCarbon

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DeCarbon 2023年 1卷

作者： Meixin Guan Hui Jin Wenwen Wei Mi Yan State Key Laboratory of Multiphase Flow in Power Engineering (SKLMF) Xi'an Jiaotong University 28 Xianning West Road Xi'an 710049 Shaanxi China State Key Laboratory of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310027 Zhejiang China

The world's marine litter consists mainly of plastic, and 99% of it does not float on the surface of the sea but on the seabed. The plastic carbon footprint necessarily includes the extraction or manufacture of raw materials, the conversion process, the distribution of products, the consumption of specific types of products and the disposal of the final product, as all these stages release carbon into the atmosphere. This work, inspired by marine microplastics and investigates how plastic waste is degraded and transformed in high-pressure, low-temperature seawater, this paper investigates the corrosion of polyethylene terephthalate (PET) and polypropylene (PP) plastics in seawater at high-pressure, using artificial seawater temperatures to simulate ocean temperatures of approximately 4 °C and time settings of 1 day–7 days. The results show that increasing the time enhances the degradation of the plastics and that changing the pressure has little effect on the degradation effect. Understanding its degradation in seawater can help us to better treat plastic waste and thus reduce the carbon footprint of the disposal process.

关键词： PET PP High-pressure seawater Degradation

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Atomically Dispersed Co Sites on BiOCl Nanosheets for Efficient CO 2 Photoreduction

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Green Energy & Environment 2025年

作者： Ting Peng Yiduo Wang Ke Wang Kaini Zhang Yiqing Wang Yufei Xu Qingqing Guan Guofu Wang Wenjie Zhang Binglan Wu Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China College of Chemical and Biological Engineering Zhejiang University Hangzhou 310058 China Institute of Zhejiang University-Quzhou Quzhou 324000 China

Efficient CO 2 photoreduction to produce fuel remains a great challenge, due to the fast recombination of photogenerated charge carriers and the lack of effective reactive sites in the developed photocatalysts. Herein, single Co atoms (Co SA ) were highly dispersed on hydrothermally synthesized BiOCl nanosheets (BOC) by a facile two-step electrostatic self-assembly and pyrolysis method. The obtained Co SA -BOC could be performed for efficient CO 2 photoreduction to stoichiometrically produce CO and O 2 at the ratio of 2:1, with the CO evolution rate reaching 45.93 μmol g –1 h –1 , ∼4 times that of the pristine BOC. This distinctly improved photocatalytic performance for Co SA -BOC should be benefited from the introduction of atomically dispersed Co-O 4 coordination structures, which could accelerate the migration of photogenerated charge carriers to surface by creating an impurity energy level in the forbidden band, and act as the reactive sites to deliver the photogenerated electrons to activate CO 2 molecules for CO production. This work provides a facile and reliable strategy to highly disperse single atoms on low-dimensional semiconductors for efficient CO 2 photoreduction to selectively produce CO.

关键词： photocatalysis CO 2 reduction BiOCl nanosheets single Co atoms

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Study on the heat and mass transfer characteristics of wet air in metal foam in the space station environment

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Applied Thermal engineering 2025年 277卷

作者： Zhu, Guowei Zhang, Liang Xia, Yujuan Zhou, Hantao School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering University of Shanghai for Science and Technology Shanghai200093 China China National Institute of Standardization Beijing100191 China

This paper has developed a novel dehumidification device for space station environment, which uses foam copper as the core, with a Stirling refrigerator providing cooling, heat pipes assisting in heat conduction and a siphon water guidance system employed to remove condensate. Experiments on dehumidifying wet air within the foam copper were then carried out under simulated microgravity dehumidification conditions. The experimental conditions included different inlet air temperatures, humidities, air velocities, and cold end temperatures of the Stirling refrigerator. The experimental research indicates that as the inlet air temperature rises from 20 °C to 30 °C, the mass transfer coefficient increases by 57.06 %, and the sensible heat coefficient rises by 10.62 %. When the air velocity increases from 0.4 m·s−1 to 1.4 m·s−1, these two coefficients increase by 111.79 % and 170.83 %, respectively. In contrast, increasing the relative humidity from 50 % to 80 % results in a 34.09 % decrease in the sensible heat coefficient, while the mass transfer coefficient increases by 11.4 %. When the cold-end temperature rises from 8 °C to 13 °C, the sensible heat transfer and mass transfer coefficients increase by 9.63 % and 4.06 %, respectively. Based on this, a sensitivity analysis was conducted using the experimental data, and heat and mass transfer correlations were fitted. The mean standard deviations of the heat and mass transfer correlations are 3.74 % and 6.30 %, respectively, indicating a high degree of fitting accuracy. This work provides a new humidity control solution for future space station thermal management systems. © 2025

关键词： Osmosis

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Prediction of the severe slugging period in gas-liquid two-phase pipeline-riser systems using an artificial neural network

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Energy 2025年 331卷

作者： Chang, Yingjie Xu, Qiang Huang, Bo Zhang, Xuemei Yu, Haiyang Chen, Hao Thévenin, Dominique Guo, Liejin Shaanxi Key Laboratory of New Transportation Energy and Automotive Energy Saving School of Energy and Electrical Engineering Chang'an University Xi'an710064 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universität Magdeburg Magdeburg39106 Germany

Severe slugging flow (SS) is a very harmful flow regime found during oil and gas transportation. An accurate prediction of the SS period would help to obtain the needed conditions for regime transition models, which are essential when designing and operating an oil and gas field. However, previous empirical correlations are limited to specific flow and structural conditions, resulting in significant errors whenever these parameters deviate. Gas-liquid two-phase flow experiments in a pipeline-riser system were carried out and used as additional training data. The analysis of scatter matrix and correlation coefficient was used to determine the most relevant features impacting SS period. Then, a prediction model based on an artificial neural network (ANN) was established with one single output (the SS period) and seven input features, including five pipeline structural parameters and two flow parameters. The prediction errors coming with previous empirical models are much larger than those of our ANN model. While the relative errors of the empirical models range from −95 % to 3000 %, the ANN has a prediction error within a range of 25 % and a mean absolute error of only 11.3 %, showing a significant improvement over previous predictions. © 2025 Elsevier Ltd

关键词： Gas industry

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Function-switchable metal/semiconductor junction enables efficient photocatalytic overall water splitting with selective water oxidation products

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Science Bulletin 2020年第16期65卷 1389-1395,M0004页

作者： Daixing Wei Yubo Tan Yiqing Wang Tingting Kong Shaohua Shen Samuel S.Maoc International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China College of Chemistry and Chemical Engineering Xi'an Shiyou UniversityXi'an 710054China Department of Mechanical Engineering University of California at BerkeleyBerkeleyCA 94720USA

A novel metal/semiconductor photocatalyst,Cu nanoparticles(NPs)modified TiO2 hollow spheres(Cu/TiO2),was designed for efficient photocatalytic overall water splitting(POWS)under both ultraviolet(UV)and visible(Vis)*** Cu/TiO2 photocatalyst possesses excellent POWS performance under Vis light at the highest level among the reported TiO2-based ***,the metal/semiconductor junction formed between Cu and TiO2 enables controlled water-oxidation product selectivity(H2O2 or O2)via different reaction pathways regulated by irradiation *** UV light,the electrons excited in TiO2 are captured by Cu NPs through the Cu/TiO2 Schottky interface for H2 production,with the photoholes in TiO2 producing H2O2 through a two-electron process;whilst under Vis light,Cu NPs act as plasmon to inject hot electrons to TiO2 for H2 production,while O2 is produced by hot holes on Cu NPs via a four-electron *** rational design of function-switchable metal/semiconductor junction may be helpful to understand the mechanisms for POWS with desired gas/liquid water-oxidation products.

关键词： Photocatalysis Water splitting Product selectivity Reaction pathway Metal/semiconductor junction

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A subcooled boiling model developed for narrow rectangular channels based on the CFD method 18

A subcooled boiling model developed for narrow rectangular c...

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18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019

作者： Li, Linfeng Wang, Mingjun Zhang, Dalin Tian, Wenxi Su, G.H. Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

The accurate prediction of subcooled boiling phenomena in narrow rectangular channels is of great importance for the plate type fuel reactor core safety analysis during some critical scenarios. Serious of experimental studies on subcooled boiling in narrow rectangular channels indicate that a bubble may slide on the heating surface after nucleation and then lift to the main flow, merging with not-yet-fully-grown bubble and disrupting local boundary layer. In this paper, the influence of sliding bubbles is taken into consideration in wall boiling model and implanted into the CFD code to simulate boiling in narrow rectangular channel. Bubble dynamics is used in calculating the relevant bubble diameters during ebulletin cycle. The feasibility of this proposed model is validated with existed experimental data by comparing wall superheat. This work could promote the development of CFD two-phase flow simulation capacity in the plate type fuel nuclear reactor. © 2019 American Nuclear Society. All rights reserved.

关键词： Computational fluid dynamics

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Low to intermediate temperature ignition delay times of nitromethane 12

Low to intermediate temperature ignition delay times of nitr...

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12th Asia-Pacific Conference on Combustion, ASPACC 2019

作者： Yang, Meng Tang, Chenglong Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road Xi'an Shaanxi710049 China

In this work, the auto-ignition experiments of nitromethane at the low to intermediate temperature, fuel concentration of 2%, pressure of 30 bar and different equivalence ratios have been investigated by using rapid compression machine. The pressure profiles of nitromethane ignition were observed. Results show that a distinct two-stage heat release process is found at ? = 0.5. And multi-stage heat release is also observed with temperature decreasing. Subsequently, the effect of equivalence ratio on the nitromethane ignition is performed. The results show that the dependence of nitromethane ignition on the equivalence ratio is weak. In addition, the experimental data are used to validate the recent developed mechanisms of nitromethane. Relative large deviations are observed between experiments and predictions. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Combustion

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